The proposal describes the current and proposed progress of an integrated series of research projects aimed at understanding the social and psychological etiological bases of adolescent drug use. The research framework involves family background variables, interpersonal processes and peer influence, situational variables, sociocultural factors, personality, and other measurable factors that have been theoretically or empirically demonstrated to be relevant to understanding the development of drug use patterns. Three specific research projects are described in detail with each project including numerous, but related, studies. Particular attention is paid to predictive, longitudinal research, causal modeling, and multimethod measurement.